Device and method of configurable synchronization signal and channel design

ABSTRACT

Devices and methods of using xSS are generally disclosed. A UE receives an xPSS with (N rep ) symbols each with a subcarrier spacing of K×a PSS subcarrier spacing and a duration of a PSS symbol/K. PSD subcarriers surround the xPSS and the ZC sequence is punctured to avoid transmission on a DC subcarrier. Guard subcarriers separate the xPSS and PSD when the ZC sequence is less than the occupied BW of the xPSS and at least one element in the ZC sequence is punctured for xPSS symbol generation otherwise. One or more xSSSs and xS-SCHs may follow the xPSS. The xSS may be omnidirectional, each having a same xPSS and different xSSS or xS-SCH or a different xPSS and same xSSS or xS-SCH or beamformed, each having different xPSSs and xSSSs or xS-SCHs or a same xPSS and different xSSS or xS-SCH.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.16/408,193, filed May 9, 2019, and titled “DEVICE AND METHOD OFCONFIGURABLE SYNCHRONIZATION SIGNAL AND CHANNEL DESIGN”, and which is acontinuation of U.S. patent application Ser. No. 15/564,859, filed Oct.6, 2017, which is a U.S. National Stage Filing under 35 U.S.C. 371 fromInternational Application No. PCT/US2015/067078, filed Dec. 21, 2015 andpublished in English as WO 2016/182602 on Nov. 17, 2016, which claimsthe benefit of priority to U.S. Provisional Patent Application Ser. No.62/159,059, filed, May 8, 2015, and entitled “PRIMARY SYNCHRONIZATIONSIGNAL DESIGN,” and U.S. Provisional Patent Application Ser. No.62/163,696, filed, May 19, 2015, and entitled “CONFIGURABLESYNCHRONIZATION SIGNAL AND CHANNEL DESIGN,” which are incorporatedherein by reference in their entirety.

The claims in the instant application are different than those of theparent application and/or other related applications. The Applicanttherefore rescinds any disclaimer of claim scope made in the parentapplication and/or any predecessor application in relation to theinstant application. Any such previous disclaimer and the citedreferences that it was made to avoid, may need to be revisited. Further,any disclaimer made in the instant application should not be read intoor against the parent application and/or other related applications.

TECHNICAL FIELD

Embodiments pertain to radio access networks. Some embodiments relate tothe synchronization of user equipment (UEs) in cellular networks,including Third Generation Partnership Project Long Term Evolution (3GPPLTE) networks and LTE advanced (LTE-A) networks as well as 4^(th)generation (4G) networks and 5^(th) generation (5G) networks. Someembodiments in particular relate to synchronization signals in 5Gnetworks, including Primary Synchronization Signals (xPSS) and SecondarySynchronization Signal (xSSS) and a Secondary-Synchronization Channel(xS-SCH).

BACKGROUND

With the increase in different types of devices communicating overnetworks to servers and other computing devices, usage of 3GPP LTEsystems has increased. In particular, as the number and complexity ofUEs has grown, users have demanded extended functionality and enhancedand varied services and applications such as telephony, messagingservices and video streaming among others. However, next generationsystems may be targeted to meet vastly different and sometimeconflicting performance constraints driven by the different services andapplications. To address vastly diverse requirements, the nextgeneration technology may evolve based on 3GPP LTE-Advanced withadditional potential new Radio Access Technologies (RATs).

Among the numerous issues involved in designing 4 and 5G LTE systems isenabling synchronization of UEs with the network. To this end, with theincrease in the types of UEs accessing network resources and for variouspurposes, it may be desirable to provide flexibility for synchronizationsignals in next generation networks.

BRIEF DESCRIPTION OF THE FIGURES

In the figures, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The figures illustrate generally, by way of example, but notby way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 is a functional diagram of a wireless network in accordance withsome embodiments.

FIG. 2 illustrates components of a communication device in accordancewith some embodiments.

FIG. 3 illustrates a block diagram of a communication device inaccordance with some embodiments.

FIG. 4 illustrates another block diagram of a communication device inaccordance with some embodiments.

FIG. 5 illustrates a system bandwidth including a primarysynchronization signal in accordance with some embodiments.

FIG. 6 illustrates a primary synchronization signal in accordance withsome embodiments.

FIG. 7 illustrates a fully loaded synchronization signal and channel inaccordance with some embodiments.

FIG. 8 illustrates a synchronization signal and channel transmission inaccordance with some embodiments.

FIG. 9 illustrates a flowchart of synchronization in accordance withsome embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1 shows an example of a portion of an end-to-end networkarchitecture of a Long Term Evolution (LTE) network with variouscomponents of the network in accordance with some embodiments. As usedherein, an LTE network refers to both LTE and LTE Advanced (LTE-A)networks as well as other versions of LTE networks to be developed. Thenetwork 100 may comprise a radio access network (RAN) (e.g., asdepicted, the E-UTRAN or evolved universal terrestrial radio accessnetwork) 101 and core network 120 (e.g., shown as an evolved packet core(EPC)) coupled together through an S1 interface 115. For convenience andbrevity, only a portion of the core network 120, as well as the RAN 101,is shown in the example.

The core network 120 may include a mobility management entity (MME) 122,serving gateway (serving GW) 124, and packet data network gateway (PDNGW) 126. The RAN 101 may include evolved node Bs (eNBs) 104 (which mayoperate as base stations) for communicating with user equipment (UE)102. The eNBs 104 may include macro eNBs 104 a and low power (LP) eNBs104 b. The eNBs 104 and UEs 102 may employ the synchronizationtechniques as described herein.

The MME 122 may be similar in function to the control plane of legacyServing GPRS Support Nodes (SGSN). The MME 122 may manage mobilityaspects in access such as gateway selection and tracking area listmanagement. The serving GW 124 may terminate the interface toward theRAN 101, and route data packets between the RAN 101 and the core network120. In addition, the serving GW 124 may be a local mobility anchorpoint for inter-eNB handovers and also may provide an anchor forinter-3GPP mobility. Other responsibilities may include lawfulintercept, charging, and some policy enforcement. The serving GW 124 andthe MME 122 may be implemented in one physical node or separate physicalnodes.

The PDN GW 126 may terminate a SGi interface toward the packet datanetwork (PDN). The PDN GW 126 may route data packets between the EPC 120and the external PDN, and may perform policy enforcement and chargingdata collection. The PDN GW 126 may also provide an anchor point formobility devices with non-LTE access. The external PDN can be any kindof IP network, as well as an IP Multimedia Subsystem (IMS) domain. ThePDN GW 126 and the serving GW 124 may be implemented in a singlephysical node or separate physical nodes.

The eNBs 104 (macro and micro) may terminate the air interface protocoland may be the first point of contact for a UE 102. In some embodiments,an eNB 104 may fulfill various logical functions for the RAN 101including, but not limited to, RNC (radio network controller functions)such as radio bearer management, uplink and downlink dynamic radioresource management and data packet scheduling, and mobility management.In accordance with embodiments, UEs 102 may be configured to communicateorthogonal frequency division multiplexed (OFDM) communication signalswith an eNB 104 over a multicarrier communication channel in accordancewith an OFDMA communication technique. The OFDM signals may comprise aplurality of orthogonal subcarriers.

The S1 interface 115 may be the interface that separates the RAN 101 andthe EPC 120. It may be split into two parts: the S1-U, which may carrytraffic data between the eNBs 104 and the serving GW 124, and theS1-MME, which may be a signaling interface between the eNBs 104 and theMME 122. The X2 interface may be the interface between eNBs 104. The X2interface may comprise two parts, the X2-C and X2-U. The X2-C may be thecontrol plane interface between the eNBs 104, while the X2-U may be theuser plane interface between the eNBs 104.

With cellular networks, LP cells 104 b may be typically used to extendcoverage to indoor areas where outdoor signals do not reach well, or toadd network capacity in areas with dense usage. In particular, it may bedesirable to enhance the coverage of a wireless communication systemusing cells of different sizes, macrocells, microcells, picocells, andfemtocells, to boost system performance. The cells of different sizesmay operate on the same frequency band, or may operate on differentfrequency bands with each cell operating in a different frequency bandor only cells of different sizes operating on different frequency bands.As used herein, the term LP eNB refers to any suitable relatively LP eNBfor implementing a smaller cell (smaller than a macro cell) such as afemtocell, a picocell, or a microcell. Femtocell eNBs may be typicallyprovided by a mobile network operator to its residential or enterprisecustomers. A femtocell may be typically the size of a residentialgateway or smaller and generally connect to a broadband line. Thefemtocell may connect to the mobile operator's mobile network andprovide extra coverage in a range of typically 30 to 50 meters. Thus, aLP eNB 104 b might be a femtocell eNB since it is coupled through thePDN GW 126. Similarly, a picocell may be a wireless communication systemtypically covering a small area, such as in-building (offices, shoppingmalls, train stations, etc.), or more recently in-aircraft. A picocelleNB may generally connect through the X2 link to another eNB such as amacro eNB through its base station controller (BSC) functionality. Thus,LP eNB may be implemented with a picocell eNB since it may be coupled toa macro eNB 104 a via an X2 interface. Picocell eNBs or other LP eNBs LPeNB 104 b may incorporate some or all functionality of a macro eNB LPeNB 104 a. In some cases, this may be referred to as an access pointbase station or enterprise femtocell.

Communication over an LTE network may be split up into 10 ms frames,each of which may contain ten 1 ms subframes. Each subframe of theframe, in turn, may contain two slots of 0.5 ms. Each subframe may beused for uplink (UL) communications from the UE to the eNB or downlink(DL) communications from the eNB to the UE. In one embodiment, the eNBmay allocate a greater number of DL communications than ULcommunications in a particular frame. The eNB may schedule transmissionsover a variety of frequency bands (f₁ and f₂). The allocation ofresources in subframes used in one frequency band and may differ fromthose in another frequency band. Each slot of the subframe may contain6-7 OFDM symbols, depending on the system used. In one embodiment, thesubframe may contain 12 subcarriers. A downlink resource grid may beused for downlink transmissions from an eNB to a UE, while an uplinkresource grid may be used for uplink transmissions from a UE to an eNBor from a UE to another UE. The resource grid may be a time-frequencygrid, which is the physical resource in the downlink in each slot. Thesmallest time-frequency unit in a resource grid may be denoted as aresource element (RE). Each column and each row of the resource grid maycorrespond to one OFDM symbol and one OFDM subcarrier, respectively. Theresource grid may contain resource blocks (RBs) that describe themapping of physical channels to resource elements and physical RBs(PRBs). A PRB may be the smallest unit of resources that can beallocated to a UE. A resource block may be 180 kHz wide in frequency and1 slot long in time. In frequency, resource blocks may be either 12×15kHz subcarriers or 24×7.5 kHz subcarriers wide. For most channels andsignals, 12 subcarriers may be used per resource block, dependent on thesystem bandwidth. In Frequency Division Duplexed (FDD) mode, both theuplink and downlink frames may be 10 ms and frequency (full-duplex) ortime (half-duplex) separated. In Time Division Duplexed (TDD), theuplink and downlink subframes may be transmitted on the same frequencyand are multiplexed in the time domain. The duration of the resourcegrid 400 in the time domain corresponds to one subframe or two resourceblocks. Each resource grid may comprise 12 (subcarriers)*14(symbols)=168 resource elements.

Each OFDM symbol may contain a cyclic prefix (CP) which may be used toeffectively eliminate Inter Symbol Interference, and a Fast FourierTransform (FFT) period. The duration of the CP may be determined by thehighest anticipated degree of delay spread. Although distortion from thepreceding OFDM symbol may exist within the CP, with a CP of sufficientduration, preceding OFDM symbols do not enter the FFT period. Once theFFT period signal is received and digitized, the receiver may ignore thesignal in the CP.

There may be several different physical downlink channels that areconveyed using such resource blocks, including the physical downlinkcontrol channel (PDCCH) and the physical downlink shared channel(PDSCH). Each subframe may be partitioned into the PDCCH and the PDSCH.The PDCCH may normally occupy the first two symbols of each subframe andcarries, among other things, information about the transport format andresource allocations related to the PDSCH channel, as well as H-ARQinformation related to the uplink shared channel. The PDSCH may carryuser data and higher layer signaling to a UE and occupy the remainder ofthe subframe. Typically, downlink scheduling (assigning control andshared channel resource blocks to UEs within a cell) may be performed atthe eNB based on channel quality information provided from the UEs tothe eNB, and then the downlink resource assignment information may besent to each UE on the PDCCH used for (assigned to) the UE. The PDCCHmay contain downlink control information (DCI) in one of a number offormats that tell the UE how to find and decode data, transmitted onPDSCH in the same subframe, from the resource grid. The DCI format mayprovide details such as number of resource blocks, resource allocationtype, modulation scheme, transport block, redundancy version, codingrate etc. Each DCI format may have a cyclic redundancy code (CRC) and bescrambled with a Radio Network Temporary Identifier (RNTI) thatidentifies the target UE for which the PDSCH is intended. Use of theUE-specific RNTI may limit decoding of the DCI format (and hence thecorresponding PDSCH) to only the intended UE.

Periodic reference signaling messages containing reference signals mayoccur between the eNB and the UEs. The downlink reference signals mayinclude cell-specific reference signal (CRS) and UE-specific referencesignals. The CRS may be used for scheduling transmissions to multipleUEs, channel estimation, coherent demodulation at the UE and handover.Other reference signals may include a channel state informationreference signal (CSI-RS) used for measurement purposes, and a DiscoveryReference Signal (DRS) specific to an individual UE. CSI-RS arerelatively sparse, occur in the PDSCH and are antenna dependent.

The Primary Synchronization Signal (PSS) and Secondary SynchronizationSignal (SSS) may be used by the UE to identify the cell using the cellID, the current subframe number, slot boundary, and duplexing mode. ThePSS and SSS may be sent in the center 6 PRBs (1.08 MHz) of the systembandwidth used by the eNB 104 a, 104 b. The PSS and SSS may betransmitted from the eNB 104 a, 104 b in a broadcast to all UEs 102 insymbol periods 6 and 5, respectively, in each of subframes 0 and 5 ofeach radio frame with a normal CP. The PSS may be used for slotsynchronization and carry one of 3 cell IDs in a group sequence; the SSSmay be used for frame synchronization and carry one of 170 unique cellidentifiers so that 510 unique combinations of cell ID and cellidentifier exist in the LTE system. As the frequency location of the PSSmay be a constant, the PSS may permit the UE 102 to synchronize to thenetwork without any a priori knowledge of the allocated bandwidth usinga correlation at the expected band to obtain the PSS/SSS.

Specifically, the PSS and SSS may be comprised of a sequence of length62 symbols, mapped to the central 62 subcarriers around the DirectCurrent (D.C.) subcarrier, the subcarrier whose frequency would be equalto the RF center frequency of the UE 102. The PSS may be constructedfrom a frequency-domain Zadoff-Chu (ZC) sequence of length 63. The UE102 may be able to obtain the physical layer cell ID and achieve slotsynchronization after the detection of the PSS. The SSS sequences may begenerated according to maximum length sequences (M-sequences), which canbe created by cycling through every possible state of a shift registerof length n. Detection of the PSS and SSS may enable time and frequencysynchronization, provide the UE with the physical layer identity of thecell and the CP length, and inform the UE whether the cell uses FDD orTDD. After detection of the PSS and SSS, the UE 102 may be able tocommunicate with the eNB 104 to receive and decode the PDCCH and anyPDSCH intended for the UE 102 and provide uplink transmissions to theeNB 104.

Two Synchronization channels may be defined for cell search. The PrimarySynchronization channel (P-SCH) carries a primary code with a value 0-2that indicates the cell ID within a cell ID group. The sequence to betransmitted on the PSS corresponding to one of the cell-IDs is generatedfrom a frequency-domain ZC sequence, which results in 3 root indexes,one each for the 3 cell-IDs. The Secondary Synchronization channel(S-SCH) carries a secondary code with a value 0-167. This indicates thecell ID group, one from 168 possible groups. The UE 102 correlates thereceived signal with the variations and identifies the maximumcorrelation value to determine the value of the codes and obtain thePhysical Cell ID of the cell and to be Radio Frame, Subframe and Slotaligned with the cell.

In some embodiments, with a non-calibrated antenna, beam-formed PSStransmission may be used for eNB antenna training. For TDD systems witha calibrated antenna, omni-repeated PSS transmissions may be consideredto further reduce the beamforming training overhead. When a beamformedPSS transmission is configured, during transmission of the PSS/SSS usingbeam scanning by the eNB 104, the UE 102 may perform a beam search andsubsequently transmit an acknowledgment (ACK) to the eNB 104 with theoptimal eNB transmission direction. The eNB 104 may respond with adirectional transmission using the indicated transmission direction. TheUE 102, having received the directional transmission may transmit to theeNB 104 an uplink physical random access channel (PRACH) using beamscanning. The eNB 104 may perform a beam search and subsequentlytransmit an ACK to the UE 102 with the optimal UE transmissiondirection. The UE 102, having received the ACK may respond with atransmission using the optimal UE transmission direction and the eNB 104may perform receiver training.

When omni-repeated PSS transmission is configured for the eNB 104,during transmission of the PSS/SSS by the eNB 104, the UE 102 mayperform course beamforming training and transmit a PRACH using a coursesector sweep without providing feedback to the eNB 104. The eNB 104 mayperform analog and digital beamforming training.

The above and other periodic messages thus not only provide informationregarding the communication channel, but also enable tracking in timeand/or frequency of communications with the UE. The uplink referencesignals may include Demodulation Reference Signals (DM-RS), which may beused to enable coherent signal demodulation at the eNB. DM-RS may betime multiplexed with uplink data and transmitted on the fourth or thirdsymbol of an uplink slot for normal or extended CP, respectively, usingthe same bandwidth as the data. Sounding Reference Signals (SRS) may beused by UEs with different transmission bandwidth to allow channeldependent uplink scheduling and may typically be transmitted in the lastsymbol of a subframe.

Embodiments described herein may be implemented into a system using anysuitably configured hardware and/or software. FIG. 2 illustratescomponents of a UE in accordance with some embodiments. At least some ofthe components shown may be used in an eNB or MME, for example, such asthe UE 102 or eNB 104 shown in FIG. 1 . The UE 200 and other componentsmay be configured to use the synchronization signals as describedherein. The UE 200 may be one of the UEs 102 shown in FIG. 1 and may bea stationary, non-mobile device or may be a mobile device. In someembodiments, the UE 200 may include application circuitry 202, basebandcircuitry 204, Radio Frequency (RF) circuitry 206, front-end module(FEM) circuitry 208 and one or more antennas 210, coupled together atleast as shown. At least some of the baseband circuitry 204, RFcircuitry 206, and FEM circuitry 208 may form a transceiver. In someembodiments, other network elements, such as the eNB may contain some orall of the components shown in FIG. 2 . Other of the network elements,such as the MME, may contain an interface, such as the S1 interface, tocommunicate with the eNB over a wired connection regarding the UE.

The application or processing circuitry 202 may include one or moreapplication processors. For example, the application circuitry 202 mayinclude circuitry such as, but not limited to, one or more single-coreor multi-core processors. The processor(s) may include any combinationof general-purpose processors and dedicated processors (e.g., graphicsprocessors, application processors, etc.). The processors may be coupledwith and/or may include memory/storage and may be configured to executeinstructions stored in the memory/storage to enable various applicationsand/or operating systems to run on the system.

The baseband circuitry 204 may include circuitry such as, but notlimited to, one or more single-core or multi-core processors. Thebaseband circuitry 204 may include one or more baseband processorsand/or control logic to process baseband signals received from a receivesignal path of the RF circuitry 206 and to generate baseband signals fora transmit signal path of the RF circuitry 206. Baseband processingcircuitry 204 may interface with the application circuitry 202 forgeneration and processing of the baseband signals and for controllingoperations of the RF circuitry 206. For example, in some embodiments,the baseband circuitry 204 may include a second generation (2G) basebandprocessor 204 a, third generation (3G) baseband processor 204 b, fourthgeneration (4G) baseband processor 204 c, and/or other basebandprocessor(s) 204 d for other existing generations, generations indevelopment or to be developed in the future (e.g., fifth generation(5G), 6G, etc.). The baseband circuitry 204 (e.g., one or more ofbaseband processors 204 a-d) may handle various radio control functionsthat enable communication with one or more radio networks via the RFcircuitry 206. The radio control functions may include, but are notlimited to, signal modulation/demodulation, encoding/decoding, radiofrequency shifting, etc. In some embodiments, modulation/demodulationcircuitry of the baseband circuitry 204 may include FFT, precoding,and/or constellation mapping/demapping functionality. In someembodiments, encoding/decoding circuitry of the baseband circuitry 204may include convolution, tail-biting convolution, turbo, Viterbi, and/orLow Density Parity Check (LDPC) encoder/decoder functionality.Embodiments of modulation/demodulation and encoder/decoder functionalityare not limited to these examples and may include other suitablefunctionality in other embodiments.

In some embodiments, the baseband circuitry 204 may include elements ofa protocol stack such as, for example, elements of an evolved universalterrestrial radio access network (EUTRAN) protocol including, forexample, physical (PHY), media access control (MAC), radio link control(RLC), packet data convergence protocol (PDCP), and/or radio resourcecontrol (RRC) elements. A central processing unit (CPU) 204 e of thebaseband circuitry 204 may be configured to run elements of the protocolstack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. Insome embodiments, the baseband circuitry may include one or more audiodigital signal processor(s) (DSP) 204 f. The audio DSP(s) 204 f may beinclude elements for compression/decompression and echo cancellation andmay include other suitable processing elements in other embodiments.Components of the baseband circuitry may be suitably combined in asingle chip, a single chipset, or disposed on a same circuit board insome embodiments. In some embodiments, some or all of the constituentcomponents of the baseband circuitry 204 and the application circuitry202 may be implemented together such as, for example, on a system on achip (SOC).

In some embodiments, the baseband circuitry 204 may provide forcommunication compatible with one or more radio technologies. Forexample, in some embodiments, the baseband circuitry 204 may supportcommunication with an evolved universal terrestrial radio access network(EUTRAN) and/or other wireless metropolitan area networks (WMAN), awireless local area network (WLAN), a wireless personal area network(WPAN). Embodiments in which the baseband circuitry 204 is configured tosupport radio communications of more than one wireless protocol may bereferred to as multi-mode baseband circuitry. In some embodiments, thedevice can be configured to operate in accordance with communicationstandards or other protocols or standards, including Institute ofElectrical and Electronic Engineers (IEEE) 802.16 wireless technology(WiMax), IEEE 802.11 wireless technology (WiFi) including IEEE 802 ad,which operates in the 60 GHz millimeter wave spectrum, various otherwireless technologies such as global system for mobile communications(GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE radioaccess network (GERAN), universal mobile telecommunications system(UMTS), UMTS terrestrial radio access network (UTRAN), or other 2G, 3G,4G, 5G, etc. technologies either already developed or to be developed.

RF circuitry 206 may enable communication with wireless networks usingmodulated electromagnetic radiation through a non-solid medium. Invarious embodiments, the RF circuitry 206 may include switches, filters,amplifiers, etc. to facilitate the communication with the wirelessnetwork. RF circuitry 206 may include a receive signal path which mayinclude circuitry to down-convert RF signals received from the FEMcircuitry 208 and provide baseband signals to the baseband circuitry204. RF circuitry 206 may also include a transmit signal path which mayinclude circuitry to up-convert baseband signals provided by thebaseband circuitry 204 and provide RF output signals to the FEMcircuitry 208 for transmission.

In some embodiments, the RF circuitry 206 may include a receive signalpath and a transmit signal path. The receive signal path of the RFcircuitry 206 may include mixer circuitry 206 a, amplifier circuitry 206b and filter circuitry 206 c. The transmit signal path of the RFcircuitry 206 may include filter circuitry 206 c and mixer circuitry 206a. RF circuitry 206 may also include synthesizer circuitry 206 d forsynthesizing a frequency for use by the mixer circuitry 206 a of thereceive signal path and the transmit signal path. In some embodiments,the mixer circuitry 206 a of the receive signal path may be configuredto down-convert RF signals received from the FEM circuitry 208 based onthe synthesized frequency provided by synthesizer circuitry 206 d. Theamplifier circuitry 206 b may be configured to amplify thedown-converted signals and the filter circuitry 206 c may be a low-passfilter (LPF) or band-pass filter (BPF) configured to remove unwantedsignals from the down-converted signals to generate output basebandsignals. Output baseband signals may be provided to the basebandcircuitry 204 for further processing. In some embodiments, the outputbaseband signals may be zero-frequency baseband signals, although thisis not a requirement. In some embodiments, mixer circuitry 206 a of thereceive signal path may comprise passive mixers, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 206 a of the transmit signalpath may be configured to up-convert input baseband signals based on thesynthesized frequency provided by the synthesizer circuitry 206 d togenerate RF output signals for the FEM circuitry 208. The basebandsignals may be provided by the baseband circuitry 204 and may befiltered by filter circuitry 206 c. The filter circuitry 206 c mayinclude a low-pass filter (LPF), although the scope of the embodimentsis not limited in this respect.

In some embodiments, the mixer circuitry 206 a of the receive signalpath and the mixer circuitry 206 a of the transmit signal path mayinclude two or more mixers and may be arranged for quadraturedownconversion and/or upconversion respectively. In some embodiments,the mixer circuitry 206 a of the receive signal path and the mixercircuitry 206 a of the transmit signal path may include two or moremixers and may be arranged for image rejection (e.g., Hartley imagerejection). In some embodiments, the mixer circuitry 206 a of thereceive signal path and the mixer circuitry 206 a may be arranged fordirect downconversion and/or direct upconversion, respectively. In someembodiments, the mixer circuitry 206 a of the receive signal path andthe mixer circuitry 206 a of the transmit signal path may be configuredfor super-heterodyne operation.

In some embodiments, the output baseband signals and the input basebandsignals may be analog baseband signals, although the scope of theembodiments is not limited in this respect. In some alternateembodiments, the output baseband signals and the input baseband signalsmay be digital baseband signals. In these alternate embodiments, the RFcircuitry 206 may include analog-to-digital converter (ADC) anddigital-to-analog converter (DAC) circuitry and the baseband circuitry204 may include a digital baseband interface to communicate with the RFcircuitry 206.

In some dual-mode embodiments, a separate radio IC circuitry may beprovided for processing signals for each spectrum, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 206 d may be afractional-N synthesizer or a fractional N/N+1 synthesizer, although thescope of the embodiments is not limited in this respect as other typesof frequency synthesizers may be suitable. For example, synthesizercircuitry 206 d may be a delta-sigma synthesizer, a frequencymultiplier, or a synthesizer comprising a phase-locked loop with afrequency divider.

The synthesizer circuitry 206 d may be configured to synthesize anoutput frequency for use by the mixer circuitry 206 a of the RFcircuitry 206 based on a frequency input and a divider control input. Insome embodiments, the synthesizer circuitry 206 d may be a fractionalN/N+1 synthesizer.

In some embodiments, frequency input may be provided by a voltagecontrolled oscillator (VCO), although that is not a requirement. Dividercontrol input may be provided by either the baseband circuitry 204 orthe applications processor 202 depending on the desired outputfrequency. In some embodiments, a divider control input (e.g., N) may bedetermined from a look-up table based on a channel indicated by theapplications processor 202.

Synthesizer circuitry 206 d of the RF circuitry 206 may include adivider, a delay-locked loop (DLL), a multiplexer and a phaseaccumulator. In some embodiments, the divider may be a dual modulusdivider (DMD) and the phase accumulator may be a digital phaseaccumulator (DPA). In some embodiments, the DMD may be configured todivide the input signal by either N or N+1 (e.g., based on a carry out)to provide a fractional division ratio. In some example embodiments, theDLL may include a set of cascaded, tunable, delay elements, a phasedetector, a charge pump and a D-type flip-flop. In these embodiments,the delay elements may be configured to break a VCO period up into Ndequal packets of phase, where Nd is the number of delay elements in thedelay line. In this way, the DLL provides negative feedback to helpensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 206 d may be configured togenerate a carrier frequency as the output frequency, while in otherembodiments, the output frequency may be a multiple of the carrierfrequency (e.g., twice the carrier frequency, four times the carrierfrequency) and used in conjunction with quadrature generator and dividercircuitry to generate multiple signals at the carrier frequency withmultiple different phases with respect to each other. In someembodiments, the output frequency may be a LO frequency (f_(LO)). Insome embodiments, the RF circuitry 206 may include an IQ/polarconverter.

FEM circuitry 208 may include a receive signal path which may includecircuitry configured to operate on RF signals received from one or moreantennas 210, amplify the received signals and provide the amplifiedversions of the received signals to the RF circuitry 206 for furtherprocessing. FEM circuitry 208 may also include a transmit signal pathwhich may include circuitry configured to amplify signals fortransmission provided by the RF circuitry 206 for transmission by one ormore of the one or more antennas 210.

In some embodiments, the FEM circuitry 208 may include a TX/RX switch toswitch between transmit mode and receive mode operation. The FEMcircuitry may include a receive signal path and a transmit signal path.The receive signal path of the FEM circuitry may include a low-noiseamplifier (LNA) to amplify received RF signals and provide the amplifiedreceived RF signals as an output (e.g., to the RF circuitry 206). Thetransmit signal path of the FEM circuitry 208 may include a poweramplifier (PA) to amplify input RF signals (e.g., provided by RFcircuitry 206), and one or more filters to generate RF signals forsubsequent transmission (e.g., by one or more of the one or moreantennas 210.

In some embodiments, the UE 200 may include additional elements such as,for example, memory/storage, display, camera, sensor, and/orinput/output (I/O) interface as described in more detail below. In someembodiments, the UE 200 described herein may be part of a portablewireless communication device, such as a personal digital assistant(PDA), a laptop or portable computer with wireless communicationcapability, a web tablet, a wireless telephone, a smartphone, a wirelessheadset, a pager, an instant messaging device, a digital camera, anaccess point, a television, a medical device (e.g., a heart ratemonitor, a blood pressure monitor, etc.), or other device that mayreceive and/or transmit information wirelessly. In some embodiments, theUE 200 may include one or more user interfaces designed to enable userinteraction with the system and/or peripheral component interfacesdesigned to enable peripheral component interaction with the system. Forexample, the UE 200 may include one or more of a keyboard, a keypad, atouchpad, a display, a sensor, a non-volatile memory port, a universalserial bus (USB) port, an audio jack, a power supply interface, one ormore antennas, a graphics processor, an application processor, aspeaker, a microphone, and other I/O components. The display may be anLCD or LED screen including a touch screen. The sensor may include agyro sensor, an accelerometer, a proximity sensor, an ambient lightsensor, and a positioning unit. The positioning unit may communicatewith components of a positioning network, e.g., a global positioningsystem (GPS) satellite.

The antennas 210 may comprise one or more directional or omnidirectionalantennas, including, for example, dipole antennas, monopole antennas,patch antennas, loop antennas, microstrip antennas or other types ofantennas suitable for transmission of RF signals. In some multiple-inputmultiple-output (MIMO) embodiments, the antennas 210 may be effectivelyseparated to take advantage of spatial diversity and the differentchannel characteristics that may result.

Although the UE 200 is illustrated as having several separate functionalelements, one or more of the functional elements may be combined and maybe implemented by combinations of software-configured elements, such asprocessing elements including digital signal processors (DSPs), and/orother hardware elements. For example, some elements may comprise one ormore microprocessors, DSPs, field-programmable gate arrays (FPGAs),application specific integrated circuits (ASICs), radio-frequencyintegrated circuits (RFICs) and combinations of various hardware andlogic circuitry for performing at least the functions described herein.In some embodiments, the functional elements may refer to one or moreprocesses operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage device, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage device may include anynon-transitory mechanism for storing information in a form readable by amachine (e.g., a computer). For example, a computer-readable storagedevice may include read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media. Some embodiments mayinclude one or more processors and may be configured with instructionsstored on a computer-readable storage device.

FIG. 3 is a block diagram of a communication device in accordance withsome embodiments. The device may be a UE or eNB, for example, such asthe UE 102 or eNB 104 shown in FIG. 1 that may be configured to trackthe UE as described herein. The physical layer circuitry 302 may performvarious encoding and decoding functions that may include formation ofbaseband signals for transmission and decoding of received signals. Thecommunication device 300 may also include medium access control layer(MAC) circuitry 304 for controlling access to the wireless medium. Thecommunication device 300 may also include processing circuitry 306, suchas one or more single-core or multi-core processors, and memory 308arranged to perform the operations described herein. The physical layercircuitry 302, MAC circuitry 304 and processing circuitry 306 may handlevarious radio control functions that enable communication with one ormore radio networks compatible with one or more radio technologies. Theradio control functions may include signal modulation, encoding,decoding, radio frequency shifting, etc. For example, similar to thedevice shown in FIG. 2 , in some embodiments, communication may beenabled with one or more of a WMAN, a WLAN, and a WPAN. In someembodiments, the communication device 300 can be configured to operatein accordance with 3GPP standards or other protocols or standards,including WiMax, WiFi, GSM, EDGE, GERAN, UMTS, UTRAN, or other 3G, 3G,4G, 5G, etc. technologies either already developed or to be developed.The communication device 300 may include transceiver circuitry 312 toenable communication with other external devices wirelessly andinterfaces 314 to enable wired communication with other externaldevices. As another example, the transceiver circuitry 312 may performvarious transmission and reception functions such as conversion ofsignals between a baseband range and a Radio Frequency (RF) range.

The antennas 301 may comprise one or more directional or omnidirectionalantennas, including, for example, dipole antennas, monopole antennas,patch antennas, loop antennas, microstrip antennas or other types ofantennas suitable for transmission of RF signals. In some MIMOembodiments, the antennas 301 may be effectively separated to takeadvantage of spatial diversity and the different channel characteristicsthat may result.

Although the communication device 300 is illustrated as having severalseparate functional elements, one or more of the functional elements maybe combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingDSPs, and/or other hardware elements. For example, some elements maycomprise one or more microprocessors, DSPs, FPGAs, ASICs, RFICs andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements may refer to one or more processes operating on oneor more processing elements. Embodiments may be implemented in one or acombination of hardware, firmware and software. Embodiments may also beimplemented as instructions stored on a computer-readable storagedevice, which may be read and executed by at least one processor toperform the operations described herein.

FIG. 4 illustrates another block diagram of a communication device inaccordance with some embodiments. In alternative embodiments, thecommunication device 400 may operate as a standalone device or may beconnected (e.g., networked) to other communication devices. In anetworked deployment, the communication device 400 may operate in thecapacity of a server communication device, a client communicationdevice, or both in server-client network environments. In an example,the communication device 400 may act as a peer communication device inpeer-to-peer (P2P) (or other distributed) network environment. Thecommunication device 400 may be a UE, eNB, PC, a tablet PC, a STB, aPDA, a mobile telephone, a smart phone, a web appliance, a networkrouter, switch or bridge, or any communication device capable ofexecuting instructions (sequential or otherwise) that specify actions tobe taken by that communication device. Further, while only a singlecommunication device is illustrated, the term “communication device”shall also be taken to include any collection of communication devicesthat individually or jointly execute a set (or multiple sets) ofinstructions to perform any one or more of the methodologies discussedherein, such as cloud computing, software as a service (SaaS), othercomputer cluster configurations.

Examples, as described herein, may include, or may operate on, logic ora number of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operations andmay be configured or arranged in a certain manner. In an example,circuits may be arranged (e.g., internally or with respect to externalentities such as other circuits) in a specified manner as a module. Inan example, the whole or part of one or more computer systems (e.g., astandalone, client or server computer system) or one or more hardwareprocessors may be configured by firmware or software (e.g.,instructions, an application portion, or an application) as a modulethat operates to perform specified operations. In an example, thesoftware may reside on a communication device readable medium. In anexample, the software, when executed by the underlying hardware of themodule, causes the hardware to perform the specified operations.

Accordingly, the term “module” is understood to encompass a tangibleentity, be that an entity that is physically constructed, specificallyconfigured (e.g., hardwired), or temporarily (e.g., transitorily)configured (e.g., programmed) to operate in a specified manner or toperform part or all of any operation described herein. Consideringexamples in which modules are temporarily configured, each of themodules need not be instantiated at any one moment in time. For example,where the modules comprise a general-purpose hardware processorconfigured using software, the general-purpose hardware processor may beconfigured as respective different modules at different times. Softwaremay accordingly configure a hardware processor, for example, toconstitute a particular module at one instance of time and to constitutea different module at a different instance of time.

Communication device (e.g., computer system) 400 may include a hardwareprocessor 402 (e.g., a central processing unit (CPU), a graphicsprocessing unit (GPU), a hardware processor core, or any combinationthereof), a main memory 404 and a static memory 406, some or all ofwhich may communicate with each other via an interlink (e.g., bus) 408.The communication device 400 may further include a display unit 410, analphanumeric input device 412 (e.g., a keyboard), and a user interface(UI) navigation device 414 (e.g., a mouse). In an example, the displayunit 410, input device 412 and UI navigation device 414 may be a touchscreen display. The communication device 400 may additionally include astorage device (e.g., drive unit) 416, a signal generation device 418(e.g., a speaker), a network interface device 420, and one or moresensors 421, such as a global positioning system (GPS) sensor, compass,accelerometer, or other sensor. The communication device 400 may includean output controller 428, such as a serial (e.g., universal serial bus(USB), parallel, or other wired or wireless (e.g., infrared (IR), nearfield communication (NFC), etc.) connection to communicate or controlone or more peripheral devices (e.g., a printer, card reader, etc.).

The storage device 416 may include a communication device readablemedium 422 on which is stored one or more sets of data structures orinstructions 424 (e.g., software) embodying or utilized by any one ormore of the techniques or functions described herein. The instructions424 may also reside, completely or at least partially, within the mainmemory 404, within static memory 406, or within the hardware processor402 during execution thereof by the communication device 400. In anexample, one or any combination of the hardware processor 402, the mainmemory 404, the static memory 406, or the storage device 416 mayconstitute communication device readable media.

While the communication device readable medium 422 is illustrated as asingle medium, the term “communication device readable medium” mayinclude a single medium or multiple media (e.g., a centralized ordistributed database, and/or associated caches and servers) configuredto store the one or more instructions 424.

The term “communication device readable medium” may include any mediumthat is capable of storing, encoding, or carrying instructions forexecution by the communication device 400 and that cause thecommunication device 400 to perform any one or more of the techniques ofthe present disclosure, or that is capable of storing, encoding orcarrying data structures used by or associated with such instructions.Non-limiting communication device readable medium examples may includesolid-state memories, and optical and magnetic media. Specific examplesof communication device readable media may include: non-volatile memory,such as semiconductor memory devices (e.g., Electrically ProgrammableRead-Only Memory (EPROM), Electrically Erasable Programmable Read-OnlyMemory (EEPROM)) and flash memory devices; magnetic disks, such asinternal hard disks and removable disks; magneto-optical disks; RandomAccess Memory (RAM); and CD-ROM and DVD-ROM disks. In some examples,communication device readable media may include non-transitorycommunication device readable media. In some examples, communicationdevice readable media may include communication device readable mediathat is not a transitory propagating signal.

The instructions 424 may further be transmitted or received over acommunications network 426 using a transmission medium via the networkinterface device 420 utilizing any one of a number of transfer protocols(e.g., frame relay, internet protocol (IP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards known as Wi-Fi®, IEEE 802.16 family ofstandards known as WiMax®), IEEE 802.15.4 family of standards, a LongTerm Evolution (LTE) family of standards, a Universal MobileTelecommunications System (UMTS) family of standards, peer-to-peer (P2P)networks, among others. In an example, the network interface device 420may include one or more physical jacks (e.g., Ethernet, coaxial, orphone jacks) or one or more antennas to connect to the communicationsnetwork 426. In an example, the network interface device 420 may includea plurality of antennas to wirelessly communicate using at least one ofsingle-input multiple-output (SIMO), MIMO, or multiple-inputsingle-output (MISO) techniques. In some examples, the network interfacedevice 420 may wirelessly communicate using Multiple User MIMOtechniques. The term “transmission medium” shall be taken to include anyintangible medium that is capable of storing, encoding or carryinginstructions for execution by the communication device 400, and includesdigital or analog communications signals or other intangible medium tofacilitate communication of such software.

Methods of generating a next generation PSS (referred to herein asxPSS), as well as a repeated transmission scheme for the xPSS and aconfiguration of the xPSS transmission for a standalone ornon-standalone system are described herein. FIG. 5 illustrates a systembandwidth including a primary synchronization signal in accordance withsome embodiments. FIG. 5 illustrates an xPSS transmission within aminimum system bandwidth 504 of an effective system bandwidth 502. Ingeneral, the xPSS transmission 510 may support the minimum systembandwidth 504 as defined in a next generation system (e.g., a 5Gsystem), which allows the UE to synchronize to the network without any apriori knowledge of the allocated bandwidth due to being disposed in apredetermined location in frequency and time. In some embodiments, thexPSS transmission bandwidth 506 may be less than the minimum systembandwidth 504 to minimize intercarrier interference. In someembodiments, the remaining subcarriers 520 within the system bandwidth502 can be left unused for Power Spectral Density (PSD) boosting toimprove the link budget for the xPSS transmission 510. The D.C.subcarrier 512 may be disposed at the center of the xPSS transmission.In some embodiments, unused subcarriers 514 may be disposed between thexPSS transmission 510 and the PSD subcarriers 520. In some embodiments,a cyclic extension 516 of a sequence (e.g. the Zadoff-Chu (ZC) sequence)forming the xPSS transmission 510 may be used at one end of the xPSStransmission 510. The cyclic extension 516 may be use at either end andmay copy the ZC sequence at the other end of the xPSS transmission 510.

A number of parameters may be used to describe the xPSS transmission.These parameters include: minimum system bandwidth for the system(BW_(min,sys)), occupied bandwidth for the xPSS transmission (BW_(PSS)),subcarrier spacing for normal transmission (Δf_(SC)), subcarrier spacingfor the xPSS transmission (Δf_(PSS,SC)), total number of subcarrierswithin the occupied bandwidth for xPSS transmission (N_(PSS)), thelength of the ZC sequence (N_(ZC)), which can be an odd value or a primenumber. Typically, subcarrier spacing for the xPSS transmission can beaggregated subcarriers for normal transmission, i.e.,Δf_(PSS,SC)=K·Δf_(SC) where K is the aggregation level. The total numberof subcarriers within the occupied bandwidth for xPSS transmission(N_(PSS)) may be indicated by, e.g.,

$N_{PSS} = {{\left\lfloor \frac{{BW}_{PSS}}{\Delta f_{{PSS},{SC}}} \right\rfloor\mspace{14mu}{or}\mspace{14mu} N_{PSS}} = {\left\lceil \frac{{BW}_{PSS}}{\Delta f_{{PSS},{SC}}} \right\rceil.}}$For instance, BW_(PSS)=18 MHz, Δf_(PSS,sc)=300 KHz and N_(PSS)=60

In some embodiments, one element of the ZC sequence may be punctured toavoid transmission on the D.C. subcarrier. In some embodiments, if thelength of the ZC sequence (N_(ZC)) is less than the total number ofsubcarriers within the occupied bandwidth for xPSS transmission(N_(PSS)) within BW_(PSS) 506, the unused subcarriers 514 at the edge ofthe BW_(PSS) 506 can be left unused. That is, the subcarriers 514surrounding the xPSS 506 to form the minimum system bandwidth 504 may beunused, providing a buffer between the PSD boosting subcarriers 520 andthe xPSS 506. In this embodiment, the xPSS sequence may be generated asfollows:

${{x_{u}(n)} = {\exp\left\{ {- \frac{j\;\pi\;{{un}\left( {n + 1} \right)}}{N_{ZC}}} \right\}}},{n = 0},1,\ldots\mspace{14mu},{\left\lfloor \frac{N_{ZC}}{2} \right\rfloor - 1}$${\exp\left\{ {- \frac{j\;\pi\;{u\left( {n + 1} \right)}\left( {n + 2} \right)}{N_{ZC}}} \right\}},{n = \left\lfloor \frac{N_{ZC}}{2} \right\rfloor},\ldots\mspace{14mu},{N_{ZC} - 2}$where u is the root index, which can be fixed or defined as a functionof physical cell identity or a virtual identity configured by higherlayers (such as through an RRC message, e.g., an RRC ConnectionReconfiguration message) either from the Primary Cell (Pcell) or theSecondary Cell (Scell). The Pcell may be the cell in which the UE eitherperforms the initial connection establishment procedure or initiates theconnection re-establishment procedure, or the cell indicated as theprimary cell in a handover procedure. The Pcell may source non-accessstratum (NAS) information such as security parameters for the UE. ThePCell may operate on a primary frequency; each SCell may thus operate ona secondary frequency, which may be configured once an RRC connection isestablished and which may be used to provide additional radio resources.

Further, the mapping of the sequence to the resource elements for xPSSgeneration can be defined as follows:

${a_{k} = {x_{u}(n)}},{n = 0},1,\ldots\mspace{14mu},{{N_{PSS} - {2k}} = {n - \left\lfloor \frac{N_{ZC}}{2} \right\rfloor + \left\lfloor \frac{N_{PSS}}{2} \right\rfloor}}$where a_(k) is the transmitted xPSS symbol on the kth subcarrier andk=0, 1, . . . , N_(PSS)−1. In addition the resource elements where

${k = 0},1,\ldots\mspace{14mu},{\left\lfloor \frac{N_{PSS}}{2} \right\rfloor - \left\lfloor \frac{N_{ZC}}{2} \right\rfloor},{N_{ZC} - 1 - \left\lfloor \frac{N_{ZC}}{2} \right\rfloor + {\left\lfloor \frac{N_{PSS}}{2} \right\rfloor\mspace{14mu}\ldots}}\mspace{14mu},{N_{PSS} - 1}$may be reserved as guard subcarriers and may not be used for thetransmission of the xPSS symbol.

In one example, for BW_(min,sys)=20 MHz, BW_(PSS)=18 MHz, Δf_(SC)=75kHz, k=4, then the total number of subcarriers within the occupied BWfor xPSS transmission, N_(PSS)=60. The ZC sequence length can be definedas N_(ZC)=57 and the xPSS symbol can be generated as follows:

${{x_{u}(n)} = {\exp\left\{ {- \frac{j\;\pi\;{{un}\left( {n + 1} \right)}}{57}} \right\}}},{n = 0},1,\ldots\mspace{14mu},27$${\exp\left\{ {- \frac{j\;\pi\;{u\left( {n + 1} \right)}\left( {n + 2} \right)}{57}} \right\}},{n = 28},\ldots\mspace{14mu},55$and the mapping of the sequence to the resource elements for xPSS symbolcan be defined as:a _(k) =x _(u)(n),n=0,1, . . . ,58k=n+2where subcarriers k=0, 1, 58, 59 may be reserved as guard subcarriersand not used for the transmission of the xPSS symbol.

In some embodiments, when the length of ZC sequence is less than thenumber of subcarriers within the xPSS transmission bandwidth 506, acyclic extension 516 of the ZC sequence may be employed for xPSSgeneration. Similarly, one element of the ZC sequence may be puncturedfor the D.C. subcarrier 512.

In this embodiment, the xPSS sequence may be generated as follows:a _(k) =x _(u)(k mod(N _(ZC)−1))where a_(k) is the transmitted xPSS symbol on the kth subcarrier andk=0, 1, . . . , N_(PSS)−1. In addition, x_(u)(n) may be generated asfollows:

${x_{u}(n)} = \left\{ \begin{matrix}{\exp\left\{ {- \frac{j\;\pi\;{{un}\left( {n + 1} \right)}}{N_{ZC}}} \right\}} & {{n = 0},1,\cdots\mspace{14mu},{\left\lfloor \frac{N_{PSS}}{2} \right\rfloor - 1}} \\{\exp\left\{ {- \frac{j\pi{u\left( {n + 1} \right)}\left( {n + 2} \right)}{N_{ZC}}} \right\}} & {{n = \left\lfloor \frac{N_{PSS}}{2} \right\rfloor},\cdots\mspace{14mu},{N_{ZC} - 2}}\end{matrix} \right.$where u is the root index, which can be fixed or defined as a functionof physical cell identity or a virtual identity configured by higherlayers either to from the Pcell or Scell.

In the above example, for BW_(min,sys)=20 MHz, BW_(PSS)=18 MHz,Δf_(SC)=75 kHz, k=4, then the total number of subcarriers within theoccupied BW for xPSS transmission N_(PSS)=60. The ZC sequence length canbe defined as N_(ZC)=57 and the xPSS symbol can be generated as follows:a_(k)=x_(u)(k mod 56), where

${{x_{u}(n)} = {\exp\left\{ {- \frac{j\;\pi\;{{un}\left( {n + 1} \right)}}{57}} \right\}}},{n = 0},1,\ldots\mspace{14mu},29$${\exp\left\{ {- \frac{j\;\pi\;{u\left( {n + 1} \right)}\left( {n + 2} \right)}{57}} \right\}},{n = 30},\ldots\mspace{14mu},55$

In some embodiments, when the length of ZC sequence is greater than orequal to the number of subcarriers within xPSS transmission bandwidth506, one or more elements in the ZC sequence may be punctured for thexPSS symbol generation. Similarly, one element of the ZC sequence may bepunctured for generation of the D.C. subcarrier 512. In this embodiment,the xPSS sequence may be generated as follows:a _(k) =x _(u)(k)where a_(k) is the transmitted xPSS symbol on the kth subcarrier andk=0, 1, . . . , N_(PSS)−1. x_(u)(n) may be generated as:

${x_{u}(n)} = \left\{ \begin{matrix}{\exp\left\{ {- \frac{j\;\pi\;{{un}\left( {n + 1} \right)}}{N_{ZC}}} \right\}} & {{n = 0},1,\cdots\mspace{14mu},{\left\lfloor \frac{N_{PSS}}{2} \right\rfloor - 1}} \\{\exp\left\{ {- \frac{j\pi{u\left( {n + 1} \right)}\left( {n + 2} \right)}{N_{ZC}}} \right\}} & {{n = \left\lfloor \frac{N_{PSS}}{2} \right\rfloor},\cdots\mspace{14mu},{N_{PSS} - 1}}\end{matrix} \right.$

In the above example, for BW_(min,sys)=20 MHz, BW_(PSS)=18 MHz,Δf_(SC)=75 kHz, k=4, then the total number of subcarriers within theoccupied BW for xPSS transmission N_(PSS)=60. The ZC sequence length canbe defined as N_(ZC)=61 and the xPSS symbol can be generated as follows:

a_(k) = x_(u)(k), where${{x_{u}(n)} = {\exp\left\{ {- \frac{j\;\pi\;{{un}\left( {n + 1} \right)}}{61}} \right\}}},{n = 0},1,\ldots\mspace{14mu},29$${\exp\left\{ {- \frac{j\;\pi\;{u\left( {n + 1} \right)}\left( {n + 2} \right)}{61}} \right\}},{n = 30},\ldots\mspace{14mu},59$

Turning to generation of a repeated xPSS signal in the time domain, insome embodiments, a larger subcarrier spacing can be employed to createa shortened OFDM symbol. Subsequently, the shortened xPSS can berepeated to improve the link budget. To keep the same or an integernumber of sampling rate, it may be desirable to specify N_(rep)=2^(N),where N>1 is an integer. In the above example, Δf_(SC)=75 kHz and thenumber of aggregated subcarriers K=8, then the aggregated subcarrierspacing can be given as Δf_(SC)=·Δf_(SC)=600 kHz. The shortened symbolis the OFDM symbol duration/K and can may be repeated N_(rep) times forthe xPSS transmission.

In some embodiments, an interleaved Frequency Division Multiple Access(IFDMA) signal structure can be adopted to generate repeated xPSSsignals in the time domain. In particular, xPSS symbols may be mapped inevery K subcarriers in the frequency domain, while the remainingsubcarriers are set to 0. This IFDMA structure with RePetition Factor(RPF) of N_(rep) may create N_(rep) repeated blocks in the time domain.Similar to the embodiments above, in some embodiments, N_(rep)=2^(N) tokeep the same or an integer number for sampling rate where N>1 is aninteger. In one example, when N_(rep)=2, xPSS symbols may be mapped toevery even subcarrier, thereby creating 2 repeated blocks in the timedomain.

To improve the link budget and compensate the loss in the centimeterwave (cmWave) and millimeter wave (mmWave) bands, either a beamformed orrepeated transmission of the xPSS signal may be used. FIG. 6 illustratesa primary synchronization signal in accordance with some embodiments. Insome embodiments, a CP 602 may be inserted only at the beginning of anxPSS transmission 600 that contains one or more xPSS symbols 610. Thelength of the CP 602 can be determined based on the shortened symbolduration and total duration of the xPSS signal transmission 600, andwhether an extended CP or a normal CP is used in the system. As shown,to accommodate for the CP all of the xPSS symbols 610 may be shortenedby the same amount, or the xPSS symbols 610 may be shortened, if at all,by different amounts. In one embodiment of the latter case, only thefirst xPSS symbol 610 may be shortened.

In some embodiments, shortened xPSS symbols 610 may be used for each ofthe xPSS symbols 610. In these embodiments, a CP 602 may be inserted ineach shortened xPSS symbol 610. This embodiment may be appropriate whenthe xPSS shortened symbol 610 is generated based on a number ofaggregated subcarriers.

In embodiments in which a CP 602 is inserted in each shortened xPSSsymbol 610, the number of aggregated subcarriers may be indicated by K.In the above example, Δf_(SC)=75 kHz, the symbol duration for normaltransmission T_(sym)=13.3 μs, and the number of repetitions for the xPSStransmission N_(rep)=8. In various examples, for K=1 (the xPSS spans thesame number of subcarriers as the data symbol), the xPSS may be 13.3 μswith a repetition that spans 8 OFDM symbols and a CP length of 7.5 μs;for K=8, the shortened xPSS symbol duration T_(xPSS)=T_(sym)/K=1.67 μs,the total xPSS repetition may span 1 OFDM symbol and the CP length maybe 0.94 μs; and for K=4, the shortened xPSS symbol durationT_(xPSS)=3.33 μs, the total xPSS repetition may span 2 OFDM symbols andthe CP length may be 1.88 μs.

For a non-standalone system, the information regarding the transmissionof the xPSS transmission can be configured by higher layer signaling(e.g., a system information broadcast (SIB) or RRC signaling) andtransmitted from the Pcell via UE-specific dedicated RRC signaling. Theconfiguration of the xPSS transmission can include at least one of thefollowing parameters: an indication of a beamformed or repeated xPSStransmission, an indication of PSD boosting for transmission of the xPSStransmission, periodicity, aggregation level and repetition level of thexPSS transmission, and an indication of normal or extended CP.

Specifically, the indication of beamformed or repeated xPSS transmissionmay also relate to whether FDD, TDD or TDD with uncalibrated antennas isused in the system. When PSD boosting for transmission of the xPSStransmission is indicated, the remaining subcarriers on the xPSS symbolswithin the system bandwidth may be left unused to improve the linkbudget of xPSS transmission. Further, either rate-matching or puncturingcan be applied on the symbol(s) for transmission of data or controlchannels. The periodicity, aggregation level, and repetition level ofthe xPSS transmission may offer flexibility on the transmission of thexPSS transmission. Depending on possible UE capability on the xPSSdetection, e.g., the number of antennas at the UE side, the eNB mayadjust one or more of the parameters (the periodicity, aggregation leveland repetition level) to allow efficient beamforming acquisition. Theindication of normal or extended CP may indicate the application on theScell. When this information is available at the UE side, fastersynchronization and beamforming acquisition may be achieved, therebyreducing the UE power consumption.

In addition to the xPSS transmission, a configurable 5G SecondarySynchronization Signal (xSSS) transmission, 5G Secondary-SynchronizationChannel (xS-SCH) transmission and channel design for a 5G system and atransmission method may be provided. In some embodiments, the generaldata structure for a synchronization channel may contain nsynchronization signals (either an xPSS transmission or an xSSStransmission). In some embodiments, the synchronization signals may befollowed by a data signal. In one example, two synchronization signalsmay be present—SS#0 can be an xPSS transmission and SS#1 can be an xSSStransmission (or xS-SCH transmission). In another example, only onesynchronization signal may be present—SS#0 can be an xPSS transmissionand the data signal can be an xS-SCH transmission. In another example,two SSs may be present without the data signal—SS#0 can be an xPSStransmission and SS#1 can be an xSSS transmission.

As above, three xPSS sequences may correspond to three physical layeridentities within each group of cells. The SSS may carry the physicallayer cell identity group, thereby permitting the UE to determine thecell identity using both values. The xSSS sequences include SSC1 andSSC2 codes, which have different cyclic shifts of a single length-31 Msequence.

Each xSSS sequence may be constructed by interleaving, in thefrequency-domain, two length-31 BPSK-modulated secondary synchronizationcodes. The xSSS codes may alternate between the first and second xSSStransmissions in each radio frame, thereby enabling the UE to determinethe radio frame timing from a single observation of an xSSStransmission.

In some embodiments, the different xPSS codes/sequences may representdifferent beamforming indexes. While the beam may be transparent to theUE, the UE may have the detected sequences stored in memory to enablecorrelation of the sequence. After a UE transmits feedback, such as anACK, containing the sequence to the eNB in response to receiving thexPSS transmission, the eNB may be able to determine which beam has beendetected by a UE based on a feedback sequence unique to each beam and onthe knowledge of the relationship between beam and sequence.

In some embodiments, the same omnidirectional xPSS transmission may berepeatedly transmitted at the eNB (using an omnidirectional antenna) toallow the UE to perform coherent or non-coherent combining over therepeated transmissions or to perform a beam search.

In some embodiments, the same xPSS transmission may be repeated at theeNB, but beamforming may be used rather than an omnidirectionaltransmission. In particular, different transmit beamforming may beapplied by the eNB for each repetition to improve the link budget andcompensate for the coverage loss. In this case, the xSSS transmissionmay be different in each repetition to allow the UE to obtain thetransmit beamforming information and discriminate between the differentxSSS transmissions. The UE, having obtained the xSSS transmissioninformation, may transmit the xSSS transmission information to the eNBin an ACK or other feedback, containing the sequence, thereby permittingthe eNB to determine which beam has been detected by a UE.

In some embodiments, different omnidirectional xPSS transmission signalsmay be transmitted over repeated transmissions by the eNB. Similar tothe beamformed xPSS transmission, different root indexes may be used bythe ZC sequence in generating the xPSS transmission for each repetition.To carry information for the physical cell identity, a limited set ofroot index patterns may be predefined in the specification. Forinstance, with 4 repetitions, the set of root indexes can be defined asfollows: Set #1: {1, 2, 3, 4}; Set #2: {5, 6, 7, 8}; and Set #3: {9, 10,11, 12}. The set of root indexes may not be limited to the aboveexample, in which the number of root indexes in the sets is the same asthe number of repetitions. In some embodiments, a greater number of rootindexes may be used than repetitions. The root index used for aparticular repetition may be randomly selected or may be selected in acontinuous fashion for each repetition set. The manner in which the rootindex is selected may change between repetition sets. In someembodiments, the selection of the root indexes may depend onauto-correlation and cross-correlation properties of the resulting ZCsequence. The ZC sequences may be generated to provide robust timingsynchronization performance in the presence of frequency offset. ThexSSS transmission signal may be the same or different in each repetitiondepending on whether omnidirectional transmission or beamformingtransmission is applied respectively. A summary of the synchronizationsignal variations and transmission types is provided in Table 1 below.

TABLE 1 xPSS xSSS or xS-SCH Transmission Repeated, different Repeated,Same Omnidirectional Repeated, Same Repeated, Different Beamforming,updated for each transmission Repeated, Different Repeated, SameOmnidirectional Repeated, Different Repeated, Different Beamforming

In some embodiments, the physical cell ID information or partialphysical cell ID information may be carried by sequence or a channel. Inembodiments in which information is carried by a sequence, when Xsequences are defined for an xSSS or xS-SCH channel transmission, eachsequence may be used to indicate Y bits of information. For instance, if4 sequences are defined for transmission, the use of sequence #1 mayindicate information bit 00, the use of sequence #2 may indicateinformation bit 01, etc. Thus, the information embedded in the sequenceused for the xSSS transmission may be extracted by the UE by correctdetection of the particular sequence used for the xSSS transmission. Asthe total amount of information carried by the sequence may be limited,this may be beneficial when the size of the physical cell identityinformation in the xSSS transmission is relatively small. For instance,the xSSS transmission may carry partial information for the physicalcell identity. As above, after detecting the xPSS transmission and xSSStransmission, the UE may be able to determine the physical cellidentity. In some embodiments, the xSSS structure may be similar to thatof an SSS.

In embodiments in which information is carried by a channel, informationmay be appended using the CRC and then encoded by channel coding used togenerate the channel. Later, modulation is employed and subsequently,modulated symbols are mapped to the corresponding resource. In someembodiments, the information may be transmitted in a dedicated 5Gsynchronization channel (xS-SCH transmission). In some embodiments, theinformation may be carried by the sequences/codes described above. Adetailed design including the data format and transmission scheme aredescribed herein; some or all the parameters indicated may be includedin different fields of the xS-SCH transmission. The parameters mayinclude physical cell identity information, a beamforming index, a timeindex, a system bandwidth, a system frame number, TDD configurationinformation, and SIB1 scheduling information.

A physical cell identity field may contain partial or full informationfor the physical cell identity. For instance, while the xPSStransmission may carry 3 identities of the physical cell identity, thexS-SCH transmission may carry information for 168 groups.

A beamforming index field may contain the beamforming index. Thebeamforming index may be applied to an xS-SCH transmission instance sothat a UE is able to determine which beamforming index has been used bythe transmitter for that instance. Different beamforming indices maycorrespond to different precoding indexes, such that each beamformingindex corresponds to a unique precoding index. For example, beamformingindices 0, 1, 2, 3 may correspond to precoding index w0, w1, w2, w3. Ingeneral, the mapping relationship between beamforming index andprecoding index may be up to the eNB implementation. For example, theabove beamforming indices 0, 1, 2, 3 may correspond to non-precoding(e.g. an omnidirectional, or quasi-omnidirectional transmission).

In some embodiments a single beamforming index may be detected by theUE; while in other embodiments multiple beamforming indexes may bedetected by the UE. Whether one or more beamforming indexes are detectedby the UE, the UE may provide the detected beamforming indexes to theeNB from the UE in a feedback signal. For example, two or more preferredbeamforming index-based feedback signals may be used in scenarios inwhich the UE is located in a direction between two beams (i.e., thecorrelation for each beamforming signal meets or exceeds a predeterminedthreshold power).

A time index field may contain a time index. The time index may be,e.g., an OFDM symbol level index, slot number, subframe number, radioframe number, or any combination thereof. If the xS-SCH transmission ispredetermined, that is always expected to occur, a time index countermay be used to specify which xS-SCH transmission was transmitted. Asabove, the UE may report one or multiple detected (or decoded) timeindices. In some embodiments, the eNB may autonomously choose arelationship between the time index and beamforming index, one or bothof which may be reported by the UE as above. The beamforming informationmay thus be transparent to the UE.

A system bandwidth field may indicate the 5G system bandwidth. A systemframe number field that may indicate partial or full information of thesystem frame number. In some embodiments, the system frame number fieldand the time index field may be combined. A TDD configuration field maycontain TDD configuration information. The TDD configuration field mayallow dynamic control of downlink and uplink traffic. Schedulinginformation of SIB1 may be contained in a SIB scheduling field. The SIBscheduling field may contain the scheduling information in the time andfrequency domain, e.g., periodicity and occasion of SIB1 transmissions.

A Cyclic Redundancy Check (CRC) may be appended to the payload of thexS-SCH transmission. In various embodiments, 8, 16 or 24 parity checkbits may be calculated based on the payload size. As specified insection 5.1.1 in TS 36.212 [2], one of the generator polynomialsg_(CRC8)(D), g_(CRC16)(D), g_(CRC24A)(D), and g_(CRC24B)(D) may beadopted for the xS-SCH transmission.

Either tail biting convolutional codes (TBCC) or turbo code (TC) in theLTE specification may be used for channel coding of the xS-SCHtransmission. As TBCC outperforms TC when the payload size is relativelysmall (e.g. <100 bits), it may be more beneficial to reuse the existingTBCC for the xS-SCH transmission. After the channel coding process hasbeen completed, rate matching may be performed to fill out the availableresource elements allocated for the xS-SCH transmission. After thechannel coding and rate-matching, scrambling may be performed torandomize the interference. In particular, the scrambling sequence countmay be initialized as a function of the partial physical cell identityinformation:c _(init) =f(N _(ID) ^((xPSS)))where N_(ID) ^((xPSS)) is the partial physical cell identity informationcarried in the xPSS transmission. The use of a scrambling sequence mayensure low cross correlation between sequences used in different cellsand the interference.

To ensure robust reception of the xS-SCH transmission, either BinaryPhase-Shift Keying (BPSK) or Quadrature Phase-Shift Keying (QPSK) may beused for modulation. Further, different waveform or multiple accessschemes may be used for the xS-SCH transmission. Examples of theseinclude Single-Carrier Frequency-Division Multiple Access (SC-FDMA),OFDMA, Filter Bank Multicarrier (FBMC), or Universal FilteredMulti-Carrier (UFMC). To enable efficient receiver processing at the UE,the same antenna port may be applied for the transmission of xPSStransmission and xS-SCH transmission. In this case, the UE may acquirethe beamformer information from the xPSS transmission and apply thisinformation for the reception of the xS-SCH transmission.

In various embodiments, the xPSS transmission and one of xSSStransmission and xS-SCH transmission may be multiplexed in afrequency-division multiplexing (FDM), time-division multiplexing (TDM),or code division multiplexing (CDM) manner. When the xS-SCH transmissionis transmitted, to allow coherent detection of the xS-SCH transmission,a predetermined set of pilot symbols may be inserted in the OFDM symbolsthat are allocated for the xS-SCH transmission.

An eNB may have full control of one or more of the xPSS, xSSS and xS-SCHtransmissions to enable configurable and opportunistic transmission ofthe synchronization signal or channel. Depending on the data traffic inthe cell, the eNB may dynamically adjust the on/off pattern or overheadof the xPSS and xSSS or xS-SCH transmission.

The UE may attempt to decode and detect the xPSS and xSSS transmissionand/or xS-SCH transmission. The detection and decoding may be based onthreshold detection or CRC checking. In one example, the xPSStransmission and xSSS transmission or xS-SCH transmission may be fullyloaded. This is to say that different cells may simultaneously transmitsuch that the xPSS transmission and xSSS transmission or xS-SCHtransmission from different cells may overlap.

FIG. 7 illustrates a fully loaded synchronization signal and channel inaccordance with some embodiments. As shown in FIG. 7 , the eNB may sendan xPSS transmission and xSSS transmission 712 (shown as an xPSStransmission for convenience) or xS-SCH transmission 714 using severalcells 702, 704, 706. The transmission of the xPSS transmission and xSSStransmission 712 and/or xS-SCH transmission 714 may collide (or overlap)among the cells 702, 704, 706 during the repetition, as shown beingfully loaded. As shown in FIG. 7 , for example each of the xPSStransmissions 712 collide among the cells 702, 704, 706 and each of thexS-SCH transmission 714 transmissions collide during the repetition. Thecells 702, 704, 706 may transmit different xPSS transmission sequencesin the same time instances to permit a UE to distinguish among the xPSStransmission and xSSS transmission or xS-SCH transmissions 712, 714. Forexample, cell #0 702 may transmit xPSS 1, cell #1 704 may transmit xPSS2 and cell #2 706 may transmit xPSS transmission 3. The duration of thexPSS transmission 712 transmission may be measured in OFDM symbols,slots, subframes or frames, for example. The xS-SCH transmission 714, asabove, may include, among others, cell ID, a time index, and a subframeand/or slot number.

FIG. 8 illustrates a synchronization signal and channel transmission inaccordance with some embodiments. In FIG. 8 , the eNB may dynamicallyadjust the on/off pattern for the transmission of the synchronizationsignal or channel among the cells. This may permit the eNB to controlwhether or not xPSS transmission and xSSS transmission or xS-SCHtransmissions 812, 814 overlap among the cells 802, 804, 806. This mayalso permit the eNB to control the interference avoidance from thedifferent synchronization signals from the different cells (transmissionpoints) by sending the signals on the different time locations. When thetransmission of the synchronization signal (xPSS transmission and xSSStransmission) or synchronization channel (xS-SCH transmission) does notcollide (i.e., do not overlap temporally) among the cells 802, 804, 806,the same xPSS transmission sequence (xPSS 1) may be transmitted by theeNB in the cells 802, 804, 806.

In some embodiments, the eNB may control the transmissions such that nocollisions occur among the cells 802, 804, 806. In some embodiments, theeNB may control the transmissions such that some collisions occur. Asshown in FIG. 8 , the transmission of the xPSS transmission and xSSStransmission 812 or xS-SCH transmission 814 may collide between cells802 and 808. In this case, cells 802 and 808 may transmit different xPSStransmission sequences, respectively as shown xPSS 1 and xPSS 2, topermit a UE receiving one or both of the xPSS transmission and xSSStransmissions 812 to distinguish among the xPSS transmission and xSSStransmissions 812. In some embodiments, the xPSS transmission and/orxSSS transmissions 812 may be different among the cells 802, 804, 806despite no collisions occurring between these cells 802, 804, 806.

FIG. 9 illustrates a flowchart of synchronization in accordance withsome embodiments. The eNB shown in any of FIGS. 1-4 may employ theflowchart shown in FIG. 9 , with the UE of FIGS. 1-4 employing similaroperations. At operation 902, the eNB may configure the xPSStransmission and transmit this information to the UE. The informationmay be configured and transmitted from the Pcell via UE-specificdedicated RRC signaling. The configuration of the xPSS signal mayinclude at least one: an indication of whether a beamformed or repeatedxPSS transmission is being used, an indication of PSD boosting fortransmission of the xPSS transmission is being used, an indication ofwhether normal or extended CP is being used, and periodicity,aggregation level and repetition level of the xPSS transmission.

The xPSS transmission bandwidth may be less than the minimum systembandwidth to minimize intercarrier interference. The remainingsubcarriers within the system bandwidth may be used for PSD boosting. AD.C. subcarrier may be disposed at the center of the xPSS transmission.If the length of the ZC sequence is less than the total number ofsubcarriers within the occupied bandwidth for xPSS transmission, theunused subcarriers may be guard subcarriers disposed between the xPSStransmission and the PSD subcarriers. In some embodiments, a cyclicextension of the ZC sequence may be used at one end of the xPSStransmission. If the length of ZC sequence is greater than or equal tothe number of subcarriers within xPSS transmission bandwidth, one ormore elements in the ZC sequence may be punctured for the xPSS symbolgeneration.

The xPSS transmission may include a plurality of xPSS symbols. A cyclicprefix may be located in the front of every xPSS symbol or only in thefront of the first xPSS symbol. Each xPSS symbol may occupy a number ofaggregated subcarriers and have a length that is inversely proportionalto the number of aggregated subcarriers. Alternatively, the xPSStransmission may have an IFDMA signal structure in which the xPSSsymbols are mapped every K subcarriers in the frequency domain. The xPSStransmission may be repeated K times.

Having configured the xPSS and transmitted this information to the UE,the PCell eNB may at operation 904 configure the xSSS and/or xS-SCHtransmissions. The general data structure may contain a predeterminednumber of xPSS and one of an xSSS transmissions or an xS-SCHtransmission.

The eNB may, in operation 904, construct the xSSS sequence interleaving,in the frequency-domain, two length-31 BPSK-modulated secondarysynchronization codes. The eNB may construct the synchronizationstructure for repeated omnidirectional or beamformed transmission. Foromnidirectional transmission the xSSS transmissions may remain the sameor different and the xPSS transmissions may be the same (e.g., to allowthe UE to perform coherent or non-coherent combining over the repeatedtransmissions) or may be different to allow the UE to differentiateamong the repetitions.

Similarly, for beamformed transmission, the instances of the repeatedxSSS transmissions may be different and the instances of the repeatedthe xPSS transmissions may be the same or may be different. Thedifferences between the beamformed transmission instances may permit theUE to determine which beamformed transmission has been detected. ThexSSS transmission may contain partial physical cell identity informationembedded in a sequence. The xS-SCH transmission may contain one or moreof the physical cell identity information, beamforming index, time indexand/or system frame number, system bandwidth, TDD configurationinformation and SIB1 scheduling information. The xS-SCH transmission maycontain a CRC appended to the payload of the xS-SCH transmission.

At operation 906, the eNB may broadcast the synchronized signal at thepredetermined time and in the predetermined subbands. As above, thebroadcast may be repeated or beamformed, dependent on the structure ofthe transmission. The eNB may transmit in different cells such that oneor more of the xPSS and xSSS/or xS-SCH overlap, in which case differentsequences may be transmitted for each of the same overlappingsynchronization signal. If neither the xPSS nor xSSS/or xS-SCH overlapsbetween cells, the same sequences may be used among the cells.

At operation 908, the eNB may receive feedback transmitted by the UE.The feedback may be an ACK signal or physical random access signal

(PRACH) indicating that the UE has received the synchronizationtransmissions.

At operation 910, the eNB may determine whether or not the feedbackcontains synchronization parameters. The synchronization parameters mayinclude xPSS, xSSS and/or xS-SCH information and may be used, as above,to determine the beamforming index or the repetition received by the UE.The parameters in the feedback may include, for example, one or more ofone or multiple beamforming indexes and a time index and/or system framenumber.

If the eNB determines at operation 912, that the feedback containsbeamforming information, the eNB may at operation 914 performbeamforming training. Multiple transmit antennas at the eNB may adjustthe overall transmission beam direction by applying different phaseshifts to the signals to be transmitted on the different antennas. Theadjustments may be based on the UE feedback.

Whether or not beamforming is used, at operation 916, the eNB maycontinue to communicate with the UE. For example, after synchronizationvia the xSS, the eNB may transmit a PDCCH and PDSCH intended for the UEafter the UE has been synchronized with the eNB. The UE may similarlytransmit a PUCCH and PUSCH to the eNB.

Example 1 is an apparatus of user equipment (UE) comprising: atransceiver arranged to communicate with an evolved NodeB (eNB); andprocessing circuitry arranged to: configure the transceiver to receive aprimary synchronization signal (xPSS) transmission and one of asecondary synchronization signal (xSSS) and a synchronization channel(xS-SCH) transmission after the xPSS transmission, comprising one of: aplurality (Nrep) of xPSS symbols each comprising an xPSS subcarrierspacing an integer times a PSS subcarrier spacing and an xPSS durationthe integer divided by a PSS duration, and an Interleaved FrequencyDivision Multiple Access (IFDMA) structure comprising sets of xPSSsymbols separated by non-xPSS symbols; obtain a physical layer cellidentification and achieve synchronization with the eNB using the xPSStransmission; and configure the transceiver to communicate with the eNBafter synchronization is achieved with the eNB.

In Example 2, the subject matter of Example 1 optionally includes thatthe xPSS transmission comprises one of: a plurality (Nrep) of xPSSsymbols each comprising an xPSS subcarrier spacing of K times a PSSsubcarrier spacing of a PSS symbol and an xPSS duration of a PSSduration of the PSS symbol divided by K, where Nrep is an integergreater than 1, and an IFDMA structure to generate repeated xPSStransmission symbols in a time domain, the xPSS symbols mapped to everyK subcarriers in a frequency domain and remaining subcarriers are set to0, where K=2^(N) and N is an integer greater than 1.

In Example 3, the subject matter of any one or more of Examples 1-2optionally include that the xPSS transmission comprises a bandwidth lessthan a minimum system bandwidth, a cyclic extension of a Zadoff-Chu (ZC)sequence forming the xPSS transmission is disposed at one end of thexPSS transmission, and an element of the ZC sequence is punctured toavoid transmission on a Direct Current subcarrier disposed at a centerof the xPSS transmission.

In Example 4, the subject matter of any one or more of Examples 1-3optionally include that the xPSS transmission comprises a bandwidth lessthan a minimum system bandwidth, within the minimum system bandwidth,Power Spectral Density (PSD) subcarriers are employed for PSD boostingsurround subcarriers of the xPSS transmission, a length of a Zadoff-Chu(ZC) sequence (NZC) that forms the xPSS transmission is less than atotal number of subcarriers within an occupied bandwidth of the xPSStransmission (NPSS), and guard subcarriers disposed between the xPSStransmission and the PSD subcarriers remain unused between the PSDsubcarriers and the xPSS transmission.

In Example 5, the subject matter of any one or more of Examples 1-4optionally include that the xPSS transmission comprises a bandwidth lessthan a minimum system bandwidth, within the minimum system bandwidth,Power Spectral Density (PSD) subcarriers are employed for PSD boostingsurround subcarriers of the xPSS transmission, a cyclic extension of aZadoff-Chu (ZC) sequence that forms the xPSS transmission is disposed atone end of the xPSS transmission, and a length of the ZC sequence (NZC)is less than a total number of subcarriers within an occupied bandwidthof the xPSS transmission (NPSS), and guard subcarriers disposed betweenthe xPSS transmission and the PSD subcarriers remain unused between thePSD subcarriers and the xPSS transmission.

In Example 6, the subject matter of any one or more of Examples 1-5optionally include that the xPSS transmission comprises a bandwidth lessthan a minimum system bandwidth, within the minimum system bandwidth,Power Spectral Density (PSD) subcarriers are employed for PSD boostingsurround subcarriers of the xPSS transmission, a length of theZadoff-Chu (ZC) sequence (NZC) is at least a total number of subcarrierswithin an occupied bandwidth of the xPSS transmission (NPSS), at leastone element in the ZC sequence is punctured for xPSS transmission symbolgeneration, and an element of the ZC sequence is punctured to avoidtransmission on a Direct Current subcarrier disposed at a center of thexPSS transmission.

In Example 7, the subject matter of any one or more of Examples 1-6optionally include that one of: the xPSS transmission comprises abandwidth less than a minimum system bandwidth, a cyclic prefix (CP) isdisposed in a first of the xPSS symbols, remaining xPSS transmissionsymbols in the xPSS transmission are free from the CP, a length of theCP is based on the xPSS duration, a total duration of the xPSStransmission, and which of an extended CP and a normal CP is used, and aCP is disposed in each of the xPSS symbols, a length of the CP based onthe xPSS duration, a total duration of the xPSS transmission, and whichof an extended CP and a normal CP is used.

In Example 8, the subject matter of any one or more of Examples 1-7optionally include that the processing circuitry is further arranged to:configure the transceiver to receive information regarding the xPSStransmission from a primary cell (Pcell) via UE-specific dedicated RadioResource Control (RRC) signaling, the information including at least oneof an indication of whether the xPSS transmission is one of a beamformedand a repeated xPSS transmission, an indication of whether PowerSpectral Density (PSD) boosting is being used for the xPSS transmission,an indication of whether a cyclic prefix (CP) is used for the xPSStransmission and a type of the CP, and a periodicity, an aggregationlevel (K) and a repetition level of the xPSS transmission.

In Example 9, the subject matter of any one or more of Examples 1-8optionally include that the processing circuitry is further arranged to:configure the transceiver to consecutively receive a plurality of xPSStransmissions and one of an xSSS and an xS-SCH transmission after thexPSS transmissions.

In Example 10, the subject matter of any one or more of Examples 1-9optionally include that the processing circuitry is further arranged to:configure the transceiver to receive a plurality of consecutivesynchronization instances, each synchronization instance comprising anxPSS transmission and a secondary synchronization signal (xSSS)transmission and being free from a synchronization channel (xS-SCH)transmission.

In Example 11, the subject matter of any one or more of Examples 9-10optionally include that the synchronization instances comprise one of:omnidirectional signals each comprising one of: a same xPSS transmissionand a different one of xSSS and xS-SCH transmission, and a differentxPSS transmission and a same one of xSSS and xS-SCH transmission, andbeamformed signals each comprising one of: a same xPSS transmission anda different one of xSSS and xS-SCH transmission, and a different xPSStransmission and a different one of xSSS and xS-SCH transmission.

In Example 12, the subject matter of any one or more of Examples 1-11optionally include that at least partial physical cell information isembedded in a sequence used for the one of the xSSS transmission andxS-SCH transmission, and the processing circuitry is further arranged toextract the at least partial physical cell information by correctlydetermining the sequence.

In Example 13, the subject matter of any one or more of Examples 1-12optionally include that the xPSS transmission and the at least one of asecondary synchronization signal (xSSS) transmission and asynchronization channel (xS-SCH) transmission are multiplexed in one ofa Frequency Division Multiplexing (FDM), Time Division Multiplexing(TDM) and Code Division Multiplexing (CDM) manner.

In Example 14, the subject matter of any one or more of Examples 1-13optionally include further comprise an antenna configured to providecommunications between the transceiver and the eNB.

Example 15 is an apparatus of an evolved NodeB (eNB) comprising: aninterface configured to communicate with a user equipment (UE); andprocessing circuitry configured to, for each cell of a plurality ofcells served by the eNB: configure the transceiver to transmit aplurality of primary synchronization signal (xPSS) transmissions and oneof a secondary synchronization signal (xSSS) and a synchronizationchannel (xS-SCH) transmission after the xPSS transmission within asubframe for the cell, each xPSS transmission comprising one of anomnidirectional xPSS transmission and a beamformed xPSS transmission;and configure the transceiver to communicate with the UE aftertransmission of the xPSS transmissions.

In Example 16, the subject matter of Example 15 optionally includes thatthe processing circuitry is further configured to: configure thetransceiver to transmit a plurality of omnidirectional synchronizationsignal (xSS) transmissions and a beamformed xSS transmissions within thesubframe that each omnidirectional xSS transmission comprises one of: asame xPSS transmission and a different one of xSSS and xS-SCHtransmission, and a different xPSS transmission and a same one of xSSSand xS-SCH transmission, and beamformed signals each comprising one of:a same xPSS transmission and a different one of xSSS and xS-SCHtransmission, and a different xPSS transmission and a different one ofxSSS and xS-SCH transmission in which one of different xPSS codes andsequences represent different beamforming indexes.

In Example 17, the subject matter of any one or more of Examples 15-16optionally include that the processing circuitry is further configuredto: embed at least partial physical cell information in a sequence usedfor the one of the xSSS transmission and xS-SCH transmission.

In Example 18, the subject matter of any one or more of Examples 15-17optionally include that the processing circuitry is further configuredto: multiplex the xPSS transmission and at least one of a secondarysynchronization signal (xSSS) transmission and a synchronization channel(xS-SCH) transmission using one of Frequency Division Multiplexing(FDM), Time Division Multiplexing (TDM) and Code Division Multiplexing(CDM).

In Example 19, the subject matter of any one or more of Examples 15-18optionally include that a synchronization channel (xS-SCH) transmissioncomprises information for physical cell identity, beamforming index,time index function, system bandwidth, system frame number, TDDconfiguration information, scheduling information of system informationblock (SIB1), and the processing circuitry is further configured to:append a Cyclic Redundancy Check (CRC) comprising one of 8, 16 and 24bits after a payload of the xS-SCH transmission, use one of tail bitingconvolutional codes (TBCC) and turbo code (TC) in channel coding of thexS-SCH transmission, perform rate matching after the channel coding tofill available resource elements allocated for the xS-SCH, scramble thexS-SCH transmission after performing the channel coding andrate-matching, and initialize a scrambling sequence based on a functionof physical cell identification carried in the xPSS transmissions.

In Example 20, the subject matter of any one or more of Examples 15-19optionally include that the processing circuitry is further arranged to:configure the transceiver to dynamically adjust an on/off pattern forthe xPSS transmissions and at least one of a secondary synchronizationsignal (xSSS) transmission and a synchronization channel (xS-SCH)transmission in each cell based on load condition in the cell.

In Example 21, the subject matter of any one or more of Examples 15-20optionally include that the processing circuitry is further arranged toat least one of: configure the transceiver to transmit: a fully loadedsynchronization signal and channel transmission in which the xPSStransmissions and the at least one of the xSSS transmission and thexS-SCH transmission in different cells are different and are transmittedsimultaneously, and an opportunistic synchronization signal and channeltransmission in which the xPSS transmissions and the at least one of thexSSS transmission and the xS-SCH transmission in different cells are thesame and are transmitted at non-overlapping times.

In Example 22, the subject matter of any one or more of Examples 15-21optionally include that each xPSS transmission comprises a bandwidthless than a minimum system bandwidth and an xPSS transmission structurecomprising a plurality (Nrep) of xPSS symbols each comprising an xPSSsubcarrier spacing of K times a PSS subcarrier spacing of a PSS symboland an xPSS duration of a PSS duration of the PSS symbol divided by K,where Nrep is an integer greater than 1, within the minimum systembandwidth, Power Spectral Density (PSD) subcarriers are employed for PSDboosting surround subcarriers of the xPSS transmission, and an elementof the ZC sequence is punctured to avoid transmission on a DirectCurrent subcarrier disposed at a center of the xPSS transmission.

In Example 23, the subject matter of any one or more of Examples 21-22optionally include that one of: a) a length of a Zadoff-Chu (ZC)sequence (NZC) that forms the xPSS transmission is less than a totalnumber of subcarriers within an occupied bandwidth of the xPSStransmission (NPSS), and guard subcarriers disposed between the xPSStransmission and the PSD subcarriers between the PSD subcarriers and thexPSS transmission one of remain unused and carry a cyclic extension, andb) a length of the ZC sequence (NZC) is at least the total number ofsubcarriers within the occupied bandwidth of the xPSS transmission(NPSS), and at least one element in the ZC sequence is punctured forxPSS transmission symbol generation.

Example 24 is a computer-readable storage medium that storesinstructions for execution by one or more processors of user equipment(UE) to communicate with an evolved NodeB (eNB), the one or moreprocessors to configure the UE to: receive a primary synchronizationsignal (xPSS) transmission, and at least one of a secondarysynchronization signal (xSSS) transmission and a synchronization channel(xS-SCH) transmission, the xPSS transmission comprising an xPSSstructure comprising a repeated structure comprising a plurality (Nrep)of xPSS symbols each comprising an xPSS subcarrier spacing of K times aPSS subcarrier spacing of a PSS symbol and an xPSS transmission durationof a PSS duration of the PSS symbol divided by K, where Nrep is aninteger greater than 1; obtain a physical layer cell identification andachieve synchronization with the eNB using the xPSS transmission and theat least one of the xSSS transmission and the xS-SCH transmission; andcommunicate with the eNB after synchronization is achieved with the eNB.

In Example 25, the subject matter of Example 24 optionally includes thateach xPSS transmission comprises a bandwidth less than a minimum systembandwidth, and Power Spectral Density (PSD) subcarriers are employed forPSD boosting surround subcarriers of the xPSS transmission, an elementof a Zadoff-Chu (ZC) sequence is punctured to avoid transmission on aDirect Current subcarrier disposed at a center of the xPSS transmission,and one of: a) a length of a Zadoff-Chu (ZC) sequence (NZC) that formsthe xPSS transmission is less than a total number of subcarriers withinan occupied bandwidth of the xPSS transmission (NPSS), and guardsubcarriers disposed between the xPSS transmission and the PSDsubcarriers between the PSD subcarriers and the xPSS transmission one ofremain unused and carry a cyclic extension, b) a length of the ZCsequence (NZC) is at least the total number of subcarriers within theoccupied bandwidth of the xPSS transmission (NPSS), and at least oneelement in the ZC sequence is punctured for xPSS transmission symbolgeneration.

Although an embodiment has been described with reference to specificexample embodiments, it will be evident that various modifications andchanges may be made to these embodiments without departing from thebroader spirit and scope of the present disclosure. Accordingly, thespecification and drawings are to be regarded in an illustrative ratherthan a restrictive sense. The accompanying drawings that form a parthereof show, by way of illustration, and not of limitation, specificembodiments in which the subject matter may be practiced. Theembodiments illustrated are described in sufficient detail to enablethose skilled in the art to practice the teachings disclosed herein.Other embodiments may be utilized and derived therefrom, such thatstructural and logical substitutions and changes may be made withoutdeparting from the scope of this disclosure. This Detailed Description,therefore, is not to be taken in a limiting sense, and the scope ofvarious embodiments is defined only by the appended claims, along withthe full range of equivalents to which such claims are entitled.

Such embodiments of the inventive subject matter may be referred toherein, individually and/or collectively, by the term “invention” merelyfor convenience and without intending to voluntarily limit the scope ofthis application to any single invention or inventive concept if morethan one is in fact disclosed. Thus, although specific embodiments havebeen illustrated and described herein, it should be appreciated that anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the above description.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, UE,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. In addition, in the foregoing DetailedDescription, it can be seen that various features are grouped togetherin a single embodiment for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as reflecting anintention that the claimed embodiments require more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed embodiment. Thus the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separate embodiment.

What is claimed is:
 1. An apparatus, comprising: at least one processorarranged to cause a user equipment (UE) to: receive, from a basestation, a first synchronization signal in a first resource of aplurality of synchronization signals in a plurality of resources,wherein the first synchronization signal includes a primarysynchronization signal (PSS) and an information channel, wherein theinformation channel includes system frame number; determine a cellidentification (ID), cell group ID and synchronization timing from thefirst synchronization signal, wherein the information channel is channelcoded, rate matched, and scrambled, and wherein the information channelis scrambled by a scrambling sequence that is initialized by a functionof the cell ID, wherein time indices associated with respectivetransmissions of the information channel have a relationship tobeamforming information; and report a detected time index based on thefirst synchronization signal.
 2. The apparatus of claim 1, wherein thePSS comprises a 5G PSS (xPSS).
 3. The apparatus of claim 1, wherein theinformation channel comprises a 5G secondary synchronization channel(xS-SCH).
 4. The apparatus of claim 1, wherein the time indices compriseone or more OFDM symbol level index, slot number, subframe number, radioframe number, or any combination thereof.
 5. The apparatus of claim 1,wherein a cyclic redundancy check of 24 bits is appended to theinformation channel.
 6. The apparatus of claim 1, wherein an on/offpattern for transmission of the first synchronization signal isdynamically adjusted.
 7. A method for synchronization signaltransmission in a radio access network by a base station, comprising: bythe base station: configuring a first synchronization signal in a firstresource of a plurality of synchronization signals in a plurality ofresources, wherein the first synchronization signal includes a primarysynchronization signal (PSS) and an information channel, wherein theinformation channel includes a system frame number; performing channelcoding, rate matching and scrambling of the information channel, whereinthe information channel is scrambled by a scrambling sequence that isinitialized by a function a cell ID; and transmitting the firstsynchronization signal according to a configurable transmission pattern,wherein a first configured transmission pattern includes fewersynchronization signal transmissions in respective time windows than asecond configured transmission pattern.
 8. The method of claim 7,wherein the PSS comprises a 5G PSS (xPSS).
 9. The method of claim 7,wherein the information channel comprises a 5G secondary synchronizationchannel (xS-SCH).
 10. The method of claim 7, wherein a relationshipexists between a time index of the information channel and beamforminginformation.
 11. The method of claim 7, wherein a cyclic redundancycheck of 24 bits is appended to the information channel.
 12. The methodof claim 7, wherein the base station receives reporting of one or moretime indices detected by a user equipment (UE).
 13. The method of claim7, wherein an on/off pattern for transmission of the firstsynchronization signal is dynamically adjusted.
 14. The method of claim7, further comprising: configuring and transmitting a secondsynchronization signal.
 15. A method, comprising: transmitting, to auser equipment (UE), a first synchronization signal in a first resourceof a plurality of synchronization signals in a plurality of resources,wherein: the first synchronization signal is useable to determine a cellidentification (ID), cell group ID and synchronization timing; and thefirst synchronization signal includes a primary synchronization signal(PSS) and an information channel, wherein the information channelincludes system frame number, wherein the information channel is channelcoded, rate matched, and scrambled, wherein the information channel isscrambled by a scrambling sequence that is initialized by a function ofthe cell ID, wherein time indices associated with respectivetransmissions of the information channel have a relationship tobeamforming information; and receiving, from the UE, a report of adetected time index based on the first synchronization signal.
 16. Themethod of claim 15, wherein the PSS comprises a 5G PSS (xPSS).
 17. Themethod of claim 15, wherein the information channel comprises a 5Gsecondary synchronization channel (xS-SCH).
 18. The method of claim 15,wherein the time indices comprise one or more OFDM symbol level index,slot number, subframe number, radio frame number, or any combinationthereof.
 19. The method of claim 15, wherein a cyclic redundancy checkof 24 bits is appended to the information channel.
 20. The method ofclaim 15, wherein an on/off pattern for transmission of the firstsynchronization signal is dynamically adjusted.